In some cases, you may want to inject a service that is a bit heavy to instantiate,
but is not always used inside your object. For example, imagine you have
a NewsletterManager and you inject a mailer service into it. Only
a few methods on your NewsletterManager actually use the mailer,
but even when you don't need it, a mailer service is always instantiated
in order to construct your NewsletterManager.

Configuring lazy services is one answer to this. With a lazy service, a
"proxy" of the mailer service is actually injected. It looks and acts
just like the mailer, except that the mailer isn't actually instantiated
until you interact with the proxy in some way.

Once you inject the service into another service, a virtual proxy with the
same signature of the class representing the service should be injected. The
same happens when calling Container::get() directly.

The actual class will be instantiated as soon as you try to interact with the
service (e.g. call one of its methods).

To check if your proxy works you can check the interface of the received object:

dump(class_implements($service));// the output should include "ProxyManager\Proxy\LazyLoadingInterface"